U.S. patent application number 10/896125 was filed with the patent office on 2006-02-09 for targeting apparatus for bone fixation device.
Invention is credited to Yechiel Gotfried.
Application Number | 20060030859 10/896125 |
Document ID | / |
Family ID | 35758389 |
Filed Date | 2006-02-09 |
United States Patent
Application |
20060030859 |
Kind Code |
A1 |
Gotfried; Yechiel |
February 9, 2006 |
Targeting apparatus for bone fixation device
Abstract
Apparatus is provided for use with a bone fixation device. The
apparatus includes a targeting device, adapted to aid in fixation
of the bone fixation device to a bone of a subject. The targeting
device includes a coupling element, adapted to couple the targeting
device to the bone fixation device. The targeting device
additionally includes a coupling assembly, adapted to hold the
coupling element and to inhibit the coupling element from exiting
the coupling assembly even when the coupling element is not coupled
to the bone fixation device.
Inventors: |
Gotfried; Yechiel;
(Kiryat-Bialik, IL) |
Correspondence
Address: |
FRISHAUF, HOLTZ, GOODMAN & CHICK, PC
767 THIRD AVENUE
25TH FLOOR
NEW YORK
NY
10017-2023
US
|
Family ID: |
35758389 |
Appl. No.: |
10/896125 |
Filed: |
July 20, 2004 |
Current U.S.
Class: |
606/99 |
Current CPC
Class: |
A61B 17/1725 20130101;
A61B 17/1778 20161101; A61B 17/1721 20130101 |
Class at
Publication: |
606/099 |
International
Class: |
A61F 2/34 20060101
A61F002/34 |
Claims
1. Apparatus for use with a bone fixation device, the apparatus
comprising a targeting device, adapted to aid in fixation of the
bone fixation device to a bone of a subject, the targeting device
comprising: a coupling element, adapted to couple the targeting
device to the bone fixation device; and a coupling assembly,
adapted to hold the coupling element, and to inhibit the coupling
element from exiting the coupling assembly even when the coupling
element is not coupled to the bone fixation device.
2. The apparatus according to claim 1, wherein the targeting device
comprises at least one radiolucent material.
3. The apparatus according to claim 1, wherein the bone fixation
device includes an intramedullary (IM) nail, and wherein the
targeting device is adapted to aid in fixation of the IM nail to
the bone.
4. The apparatus according to claim 1, wherein the bone fixation
device includes a plate, and wherein the targeting device is
adapted to aid in fixation of the plate to the bone.
5. The apparatus according to claim 1, wherein the bone fixation
device includes at least one anchoring screw, and wherein the
targeting device is shaped so as to define at least one transverse
hole therethrough, for aiding in aligning the anchoring screw with
the bone fixation device.
6. The apparatus according to claim 1, wherein the coupling element
comprises a screw.
7. The apparatus according to claim 1, wherein the coupling element
comprises a snap-like coupling element.
8. The apparatus according to claim 1, wherein the coupling element
comprises metal.
9. The apparatus according to claim 1, wherein the coupling
assembly comprises at least one radiopaque material.
10. The apparatus according to claim 1, wherein the targeting
device comprises a support element shaped so as to define a support
region, which region is adapted to engage the coupling element when
the coupling element is coupled to the bone fixation device.
11. The apparatus according to claim 1, wherein the targeting
device is shaped to define a longitudinal axis thereof in a portion
of the targeting device that couples with the bone fixation device,
wherein the bone fixation device is shaped to define a longitudinal
axis thereof, and wherein the longitudinal axis of the portion of
the targeting device diverges by an angle greater than 2 degrees
from the longitudinal axis of the bone fixation device when the
coupling element is coupling the targeting device to the bone
fixation device.
12. The apparatus according to claim 1, wherein the coupling
assembly is shaped so as to define a chamber that is adapted to
hold the coupling element.
13. The apparatus according to claim 12, wherein the chamber is
shaped so as to define one or more holes extending between inside
the chamber and outside of the targeting device.
14. The apparatus according to claim 1, wherein the coupling
assembly is shaped so as to define a blocking element that is
adapted to inhibit the coupling element from exiting the coupling
assembly.
15. The apparatus according to claim 14, wherein the coupling
element is shaped so as to define a coupling surface at a distal
end thereof, and such that a portion of the coupling element that
includes the coupling surface is proximal to the blocking
element.
16. The apparatus according to claim 14, wherein the blocking
element is generally cylindrical in shape, and defines a bore
through which access is provided to a proximal end of the coupling
element.
17. The apparatus according to claim 14, wherein the blocking
element is shaped so as to define a protrusion from an inner
surface of the coupling assembly.
18. The apparatus according to claim 1, wherein the coupling
element has a proximal end and a distal end, and wherein a distance
between the proximal end and the distal end is less than about 15
mm.
19. The apparatus according to claim 18, wherein the distance is
less than about 11 mm.
20. The apparatus according to claim 19, wherein the distance is
less than about 9 mm.
21. The apparatus according to claim 1, wherein the coupling
element has a proximal coupling element end, wherein the targeting
device is shaped so as to define an elongated bore having a distal
bore end and, at a proximal bore end thereof, a proximal opening,
wherein the coupling assembly is positioned in a vicinity of the
distal bore end, and wherein a distance from the proximal coupling
element end to the proximal bore end is greater than about 25 mm,
when the coupling element couples the targeting device to the bone
fixation device.
22. The apparatus according to claim 21, wherein the distance is
greater than about 30 mm.
23. The apparatus according to claim 22, wherein the distance is
greater than about 35 mm.
24. The apparatus according to claim 23, wherein the distance is
greater than about 45 mm.
25. Apparatus for use with a bone fixation device, the apparatus
comprising a targeting device, adapted to aid in fixation of the
bone fixation device to a bone of a subject, the targeting device
shaped so as to define an elongated bore having a proximal opening
at a proximal bore end thereof, and comprising: a coupling element
having distal and proximal coupling element ends, the coupling
element adapted to be insertable into the bore via the proximal
opening, and to couple the targeting device to the bone fixation
device, the coupling element and bore shaped such that a coupling
element length between the distal coupling element end and the
proximal coupling element end is less than about 30 mm, and a bore
distance between the proximal coupling element end and the proximal
bore end is greater than about 25 mm when the coupling element
couples the targeting device to the bone fixation device.
26. The apparatus according to claim 25, wherein the targeting
device is shaped to define a longitudinal axis thereof in a portion
of the targeting device that couples with the bone fixation device,
wherein the bone fixation device is shaped to define a longitudinal
axis thereof, and wherein the longitudinal axis of the portion of
the targeting device diverges by an angle greater than 2 degrees
from the longitudinal axis of the bone fixation device when the
coupling element is coupling the targeting device to the bone
fixation device.
27. The apparatus according to claim 25, wherein the coupling
element comprises a screw.
28. The apparatus according to claim 25, wherein the targeting
device comprises at least one radiolucent material.
29. The apparatus according to claim 25, wherein the bone fixation
device includes an intramedullary (IM) nail, and wherein the
targeting device is adapted to aid in fixation of the IM nail to
the bone.
30. The apparatus according to claim 25, wherein the bone fixation
device includes a plate, and wherein the targeting device is
adapted to aid in fixation of the plate to the bone.
31. The apparatus according to claim 25, wherein the coupling
element length is less than about 15 mm.
32. The apparatus according to claim 31, wherein the coupling
element length is less than about 11 mm.
33. The apparatus according to claim 32, wherein the coupling
element length is less than about 9 mm.
34. The apparatus according to claim 25, wherein the bore distance
is greater than about 30 mm.
35. The apparatus according to claim 34, wherein the bore distance
is greater than about 35 mm.
36. The apparatus according to claim 35, wherein the bore distance
is greater than about 45 mm.
37. A method for coupling a bone fixation device to a targeting
device, the targeting device adapted to aid in fixation of the bone
fixation device to a bone of a subject, comprising: coupling the
targeting device to the bone fixation device by means of a coupling
assembly that includes a coupling element, the coupling assembly
being adapted to hold the coupling element, and to inhibit the
coupling element from exiting the coupling assembly even when the
coupling element is not coupled to the bone fixation device.
38. A method for coupling a bone fixation device to a targeting
device, the targeting device adapted to aid in fixation of the bone
fixation device to a bone of a subject, and the targeting device
shaped so as to define an elongated bore having a proximal opening
at a proximal bore end thereof, the method comprising: inserting,
into the bore via the proximal opening, a coupling element having
distal and proximal coupling element ends; and coupling the
targeting device to the bone fixation device, using the coupling
element, the coupling element and bore shaped such that a coupling
element length between the distal coupling element end and the
proximal coupling element end is less than about 30 mm, and a bore
distance between the proximal coupling element end and the proximal
bore end is greater than about 25 mm when the coupling element
couples the targeting device to the bone fixation device.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to implantable
devices for treating bone fractures, and specifically to a
targeting device for implanting a bone fixation device.
BACKGROUND OF THE INVENTION
[0002] Intramedullary (IM) nails are implantable devices used to
stabilize fractures and allow for bone healing. IM nails are
inserted into the medullary canal of the long bones of the
extremities, e.g., the femur, tibia, or humerus. Currently-used IM
nails have a head region that generally includes at least one hole,
transverse to the longitudinal axis of the nail, for receiving
anchoring means, such as a screw, to secure the nail within the
medullary canal of the bone.
[0003] Reference is made to FIG. 1, which is a schematic
illustration of a targeting device 10, as known in the prior art.
Targeting device 10 is used to align one or more IM anchoring
screws (not shown) with transverse holes 12 of an IM nail 14, by
inserting the IM anchoring screws and/or a drill bit through
corresponding aligned transverse holes 16 in targeting device 10.
IM nail 14 is inserted into a medullary canal, and targeting device
10 is attached to a proximal end 18 of the IM nail, typically by a
screw 20. Screw 20 is inserted into a screw hole 22 at the time of
attachment of targeting device 10 to IM nail 14, such that a
proximal end 24 of the screw is readily accessible from outside the
screw hole. A conventional screwdriver 26 is typically used to
tighten screw 20 into IM nail 14.
[0004] It is typical to take radiographic images, such as X-ray or
fluoroscopic images, during the IM nail implantation procedure, in
order to check the alignment of the IM anchoring screws before
drilling through the bone. At least a portion of targeting device
10 typically comprises a radiolucent material, such as carbon, in
order to minimize the interference of the targeting device with the
radiographic images. Screw 20, however, typically comprises a
radiopaque metal. Although metal interferes with the radiographic
imaging, its use is considered necessary to provide strong coupling
between targeting device 10 and IM nail 14.
[0005] U.S. Pat. No. 6,183,477 to Pepper, which is incorporated
herein by reference, describes an attachment tool for attaching a
drill guide to a medical implant such as an intramedullary nail.
The attachment tool includes a first end and a housing. The first
end includes a first opening that allows a fastener to pass through
and thread into the implant, thereby attaching the tool. The
housing includes a second opening whose longitudinal axis is
preferably offset from the longitudinal axis of the first opening.
The housing also includes a guide surface with a groove for
directing a driving tool to the second opening. The driving tool is
inserted through the second opening to drive the fastener. The
driving tool can be inserted and removed during the procedure. The
housing also includes a plurality of holes that can be used as
drill guide holes or to attach separate drill guides or other
orthopedic devices.
[0006] U.S. Pat. No. 5,334,192 to Behrens, which is incorporated
herein by reference, describes a targeting device for attachment to
an implant for treating fractures, such as an intramedullary nail.
The targeting device has a targeting arm that extends substantially
parallel to the nail, and has a plurality of targeting bores for
receiving a drill sleeve, such targeting bores extending at
different angles with respect to the axis of the targeting arm.
[0007] European Patent EP 0 257 118 B1 to Grosse et al., which is
incorporated herein by reference, describes an intramedullary femur
nail, and a femur neck screw retained and guided in a transverse
throughbore of the femur nail.
[0008] U.S. Pat. No. 5,176,681 to Lawes et al., which is
incorporated herein by reference, describes an intramedullary
intertrochanteric fracture fixation appliance comprising an
intramedullary rod having an angulated opening to receive a femoral
neck screw. The rod has a co-axial bore extending into the
angulated opening, and anti-rotation means located in the bore to
selectively prevent rotation of the neck screw in the rod. The open
end of the bore is provided with means to positively locate a
removable fitting device on the proximal end of the rod, and so
that the anti-rotation means can be operated with the fitting
device in position.
[0009] U.S. Pat. No. 6,656,189 to Wilson et al., which is
incorporated herein by reference, describes a radiolucent aiming
guide for locating and drilling through the holes in the distal end
of an implanted intramedullary nail. The aiming guide comprises an
elongate handle constructed substantially of a radiolucent
material, which does not cast a strong image on a monitor when
exposed to radiation. The radiolucent handle is used in conjunction
with a protection sleeve, trocar, drill sleeve, and drill bit,
which are used to locate and drill through the hole in the nail.
Radiopaque components in the distal end of the protection sleeve,
trocar, and drill bit are used to align the drill over the nail
hole. A pair of radiopaque pins, located within the handle and
lying parallel to its longitudinal axis, aid in ensuring the proper
rotational alignment of the aiming guide over the nail hole. The
aiming guide may also include a structure to facilitate its
alignment over a second hole in the distal end of the
intramedullary nail.
[0010] U.S. Pat. No. 5,728,128 to Crickenberger et al., which is
incorporated herein by reference, describes a femoral neck
anteversion guide for use with a femur having a prepared
intramedullary canal. The guide includes a radiolucent stem having
a distal end for inserting into the prepared intramedullary canal,
and a radiopaque angle locator wire embedded within the stem at a
known angle for allowing the femoral neck angle and femoral neck
anteversion to be determined. The femoral neck anteversion guide
preferably includes a handle, which is attached to the radiolucent
stem by a radiolucent screw.
[0011] U.S. Pat. No. 5,403,321 to DiMarco, which is incorporated
herein by reference, describes a radiolucent drill guide for
connection to the proximal end portion of an intramedullary nail
for aligning a drill with bores of an intramedullary nail when the
nail is surgically positioned within an intramedullary canal of a
patient. The drill guide includes a handle member of radiolucent
material and a guide barrel embedded within the handle. The handle
includes an inner generally cylindrical bore and an outer surface
that is bonded to closely surround the radiolucent material of the
handle member so that the barrel does not rotate freely relative to
the handle. The guide barrel includes flanges for preventing
relative movement of the barrel in the direction of the central
longitudinal axis of the bore of the barrel. A plurality of
openings in the handle are at positions spaced away from the barrel
for guiding drills when the barrel is affixed to the intramedullary
nail so that the drills align with selected openings of the
intramedullary nail.
[0012] U.S. Pat. No. 5,178,621 to Cook et al., which is
incorporated herein by reference, describes a targeting device that
includes a radio-transparent handle and a metal snap fit barrel.
The radio-transparent handle reduces obstructions in the
radiographic image to provide a clearer image to the surgeon for
proper placement of the locking screws. The metal snap fit barrel
is retained in the handle by an interference fit between the handle
and biased keys carried by the barrel.
[0013] U.S. Pat. No. 4,827,917 to Brumfield, which is incorporated
herein by reference, describes an IM system including a screw and
an intramedullary rod. The screw has a threaded portion and a
smooth portion, and the rod has a head, stem and a longitudinal
bore. There is at least one pair of coaxial holes through the stem,
transverse to the longitudinal axis of the rod, for receiving first
anchoring means, such as a nail, screw or bolt, to secure the rod
within the marrow canal of the femur. There are at least a proximal
pair of coaxial holes and a distal pair of coaxial holes in the
head of the rod in an angled direction toward the femoral head
relative to the longitudinal axis of the rod. The distal pair of
head holes are adapted to slidingly receive the screw so as to
permit the threaded portion of the screw, in use, to engage the
femoral head and to allow sliding compression of a femoral neck or
intertrochanteric fracture.
[0014] U.S. Pat. No. 5,032,125 to Durham et al., which is
incorporated herein by reference, describes an IM hip screw that
includes an IM rod, a lag screw and a sleeve for slidably receiving
the lag screw. The sleeve is received in a passage in the IM rod
having an axis positioned at an angle relative to the longitudinal
axis of the IM rod such that the axis of the sleeve is directed
toward the head of the femur. The IM hip screw is described as
permitting sliding compression of selected fractures, particularly
intertrochanteric fractures and fractures of the femoral neck.
[0015] U.S. Pat. No. 6,443,954 to Bramlet et al., which is
incorporated herein by reference, describes an IM system that
includes a lag screw assembly extending through a radial bore in an
IM nail.
[0016] U.S. Pat. No. 6,235,031 to Hodgeman et al., which is
incorporated herein by reference, describes an IM system that
includes an IM rod, a lag screw, and a lag screw collar.
[0017] US Patent Application Publication 2002/0151898 to Sohngen et
al., which is incorporated herein by reference, describes an IM
nail having a modular configuration, including a nail member having
a chamber formed on the proximal end thereof.
[0018] US Patent Application Publication 2002/0156473 to Bramlet et
al., which is incorporated herein by reference, describes an IM
system that includes an IM nail for insertion in the femur. The
nail has an axial bore and an intersecting transverse bore. A lag
screw is inserted through the transverse bore and turned into the
head of the femur. A slotted sleeve is inserted over the lag screw
and through the transverse bore with the slots aligned with the
axial bore. A sleeve lock is inserted into the axial bore, and has
a locking tab which engages the slots in the sleeve preventing
rotational and longitudinal movement between the sleeve and the
nail. A compression screw is turned into the trailing end of the
lag screw and engages the encircling sleeve to provide longitudinal
translation between the lag screw and sleeve to apply compressive
force across a fracture.
[0019] European Patent Application Publication EP 0 521 600 to
Lawes, which is incorporated herein by reference, describes an IM
system that includes an IM rod having an angulated opening to
receive a femoral neck screw having a threaded portion at its
distal end, and locking means acting between the neck screw and the
wall of the angulated opening to prevent relative rotation between
the screw and the rod.
[0020] PCT Publication WO 02/083015 to Ferrante et al., which is
incorporated herein by reference, describes an orthopedic screw
having a screw head, a screw body with a distal tip, a shank with
an enlarged diameter at the trailing end and a thread extending
radially outward from the shank, and an internal capture surface.
The screw is used with an orthopedic implant system, which includes
an orthopedic implant and a driver capable of engaging the internal
capture of the screw.
SUMMARY OF THE INVENTION
[0021] In some embodiments of the present invention, a targeting
device, for aiding in the fixation of a bone fixation device to a
bone, comprises a coupling assembly for coupling the targeting
device to the bone fixation device. The coupling assembly is
typically shaped so as to define a retaining arrangement, such as a
chamber, pin, or screw assembly, adapted to hold a coupling
element, such as a screw, and to prevent the coupling element from
exiting the coupling assembly even when the coupling element is not
coupled to the bone fixation device. This arrangement enables the
coupling element to be shorter than conventional screws used for
similar purposes in conventional targeting devices.
[0022] Typically, a large portion of the targeting device comprises
a radiolucent material, such as carbon, and the coupling element
comprises a strong, radiopaque substance, such as a metal, in order
to strongly couple the targeting device to the bone fixation
device. Because the coupling element is shorter than conventional
screws used for similar purposes in conventional targeting devices,
the coupling element creates substantially less interference with
radiographic images than do such conventional screws.
[0023] There is therefore provided, in accordance with an
embodiment of the present invention, apparatus for use with a bone
fixation device, the apparatus including a targeting device,
adapted to aid in fixation of the bone fixation device to a bone of
a subject, the targeting device including:
[0024] a coupling element, adapted to couple the targeting device
to the bone fixation device; and
[0025] a coupling assembly, adapted to hold the coupling element,
and to inhibit the coupling element from exiting the coupling
assembly even when the coupling element is not coupled to the bone
fixation device.
[0026] In an embodiment, the targeting device includes at least one
radiolucent material.
[0027] In an embodiment, the bone fixation device includes an
intramedullary (IM) nail, and the targeting device is adapted to
aid in fixation of the IM nail to the bone.
[0028] In an embodiment, the bone fixation device includes a plate,
and the targeting device is adapted to aid in fixation of the plate
to the bone.
[0029] In an embodiment, the bone fixation device includes at least
one anchoring screw, and the targeting device is shaped so as to
define at least one transverse hole therethrough, for aiding in
aligning the anchoring screw with the bone fixation device.
[0030] In an embodiment, the coupling element includes a screw.
[0031] In an embodiment, the coupling element includes a snap-like
coupling element.
[0032] In an embodiment, the coupling element includes metal.
[0033] In an embodiment, the coupling assembly includes at least
one radiopaque material.
[0034] In an embodiment, the targeting device includes a support
element shaped so as to define a support region, which region is
adapted to engage the coupling element when the coupling element is
coupled to the bone fixation device.
[0035] In an embodiment:
[0036] the targeting device is shaped to define a longitudinal axis
thereof in a portion of the targeting device that couples with the
bone fixation device,
[0037] the bone fixation device is shaped to define a longitudinal
axis thereof, and
[0038] the longitudinal axis of the portion of the targeting device
diverges by an angle greater than 2 degrees from the longitudinal
axis of the bone fixation device when the coupling element is
coupling the targeting device to the bone fixation device.
[0039] In an embodiment, the coupling assembly is shaped so as to
define a chamber that is adapted to hold the coupling element.
[0040] In an embodiment, the chamber is shaped so as to define one
or more holes extending between inside the chamber and outside of
the targeting device.
[0041] In an embodiment, the coupling assembly is shaped so as to
define a blocking element that is adapted to inhibit the coupling
element from exiting the coupling assembly.
[0042] In an embodiment, the coupling element is shaped so as to
define a coupling surface at a distal end thereof, and such that a
portion of the coupling element that includes the coupling surface
is proximal to the blocking element.
[0043] In an embodiment, the blocking element is generally
cylindrical in shape, and defines a bore through which access is
provided to a proximal end of the coupling element.
[0044] In an embodiment, the blocking element is shaped so as to
define a protrusion from an inner surface of the coupling
assembly.
[0045] In an embodiment, the coupling element has a proximal end
and a distal end, and a distance between the proximal end and the
distal end is less than about 15 mm. In an embodiment, the distance
is less than about 11 mm. In an embodiment, the distance is less
than about 9 mm.
[0046] In an embodiment:
[0047] the coupling element has a proximal coupling element
end,
[0048] the targeting device is shaped so as to define an elongated
bore having a distal bore end and, at a proximal bore end thereof,
a proximal opening,
[0049] the coupling assembly is positioned in a vicinity of the
distal bore end, and
[0050] a distance from the proximal coupling element end to the
proximal bore end is greater than about 25 mm, when the coupling
element couples the targeting device to the bone fixation
device.
[0051] In an embodiment, the distance is greater than about 30 mm.
In an embodiment, the distance is greater than about 35 mm. In an
embodiment, the distance is greater than about 45 mm.
[0052] There is further provided, in accordance with an embodiment
of the present invention, apparatus for use with a bone fixation
device, the apparatus including a targeting device, adapted to aid
in fixation of the bone fixation device to a bone of a subject, the
targeting device shaped so as to define an elongated bore having a
proximal opening at a proximal bore end thereof, and including:
[0053] a coupling element having distal and proximal coupling
element ends, the coupling element adapted to be insertable into
the bore via the proximal opening, and to couple the targeting
device to the bone fixation device,
[0054] the coupling element and bore shaped such that a coupling
element length between the distal coupling element end and the
proximal coupling element end is less than about 30 mm, and a bore
distance between the proximal coupling element end and the proximal
bore end is greater than about 25 mm when the coupling element
couples the targeting device to the bone fixation device.
[0055] There is still further provided, in accordance with an
embodiment of the present invention, a method for coupling a bone
fixation device to a targeting device, the targeting device adapted
to aid in fixation of the bone fixation device to a bone of a
subject, including:
[0056] coupling the targeting device to the bone fixation device by
means of a coupling assembly that includes a coupling element, the
coupling assembly being adapted to hold the coupling element, and
to inhibit the coupling element from exiting the coupling assembly
even when the coupling element is not coupled to the bone fixation
device.
[0057] There is yet further provided, in accordance with an
embodiment of the present invention, a method for coupling a bone
fixation device to a targeting device, the targeting device adapted
to aid in fixation of the bone fixation device to a bone of a
subject, and the targeting device shaped so as to define an
elongated bore having a proximal opening at a proximal bore end
thereof, the method including:
[0058] inserting, into the bore via the proximal opening, a
coupling element having distal and proximal coupling element ends;
and
[0059] coupling the targeting device to the bone fixation device,
using the coupling element,
[0060] the coupling element and bore shaped such that a coupling
element length between the distal coupling element end and the
proximal coupling element end is less than about 30 mm, and a bore
distance between the proximal coupling element end and the proximal
bore end is greater than about 25 mm when the coupling element
couples the targeting device to the bone fixation device.
[0061] The present invention will be more fully understood from the
following detailed description of embodiments thereof, taken
together with the drawings, in which:
BRIEF DESCRIPTION OF THE DRAWINGS
[0062] FIG. 1 is a schematic illustration of a targeting device, as
is known in the prior art;
[0063] FIG. 2 is a schematic illustration of a targeting device, in
accordance with an embodiment of the present invention;
[0064] FIGS. 3A and 3B are schematic illustrations of
configurations of a coupling assembly, in accordance with
embodiments of the present invention;
[0065] FIG. 4 is a schematic illustration of a snap-like coupling
element, in accordance with an embodiment of the present invention;
and
[0066] FIG. 5 is a schematic illustration of another targeting
device, in accordance with an embodiment of the present
invention.
DETAILED DESCRIPTION OF EMBODIMENTS
[0067] FIG. 2 is a schematic illustration of a targeting device 40,
in accordance with an embodiment of the present invention.
Targeting device 40 typically comprises a coupling portion 42 and
an elongated alignment portion 44. For some applications, coupling
portion 42 and alignment portion 44 are separate components that
are coupled together, either during manufacture or during use,
while for other applications, targeting device 40 is formed as an
integrated unit that is shaped so as to define coupling portion 42
and alignment portion 44. Typically, a large portion of targeting
device 40, e.g., at least about 95%, 90%, or 75% by volume,
comprises at least one radiolucent material, such as carbon, carbon
fiber composite, or thermoplastic (e.g., Delrin.RTM.). For example,
substantially all (i.e., at least about 95% by volume) of alignment
portion 44 may comprise at least one radiolucent material, and a
large portion (i.e., at least about 95%, 90%, or 75% by volume) of
alignment portion 44 may comprise at least one radiolucent
material.
[0068] Targeting device 40 is adapted to aid in the fixation of a
bone fixation device 48 to a bone of a subject. Typically,
targeting device 40 is used to align one or more anchoring screws
(not shown) with transverse holes 46 of bone fixation device 48
after the device has been applied to a fractured bone. For some
applications, bone fixation device 48 comprises an intramedullary
(IM) nail, which is inserted into a medullary canal of a bone, such
as a femur. Alternatively, bone fixation device 48 comprises a
plate or other bone fixation device known in the art. Coupling
portion 42 of targeting device 40 is attached to a proximal end 50
of bone fixation device 48, and the anchoring screws and/or a drill
bit are guided through holes 52 in alignment portion 44, which
holes are aligned with corresponding transverse holes 46 of bone
fixation device 48.
[0069] A distal portion 60 of coupling portion 42 of targeting
device 40 comprises a coupling assembly 62 for coupling portion 42
to proximal end 50 of bone fixation device 48. Coupling assembly 62
is typically shaped so as to define a chamber 64 adapted to hold a
coupling element 66, such as a screw 67, as shown in FIG. 2.
Chamber 64 includes sufficient space to hold coupling element 66
even when the coupling element is not coupled to proximal end 50 of
bone fixation device 48. Typically, coupling assembly 62 is
configured to prevent coupling element 66 from exiting the coupling
assembly even when the coupling element is not coupled to proximal
end 50. For example, a distal end 68 of a blocking element 70 may
block coupling element 66 from exiting chamber 64. For example,
blocking element 70 may be generally cylindrically shaped, and may
surround and define a bore 72, as shown in FIG. 2.
[0070] A distal end of coupling element 66 is shaped so as to
define a coupling surface 74 for securing coupling element 66 to a
surface in proximal end 50 of bone fixation device 48. For example,
when coupling element 66 comprises screw 67, coupling surface 74
may be shaped so as to define a screw thread. A proximal end of
coupling element 66 is shaped so as to define an engagement surface
76, such as an indentation, for receiving a distal end 78 of an
activator tool 80. For example, engagement surface 76 and distal
end 78 may be hexagonal, square, slotted, or any other shape
appropriate for engagement. Activator tool 80 comprises an
elongated shaft 82 that is shaped and sized so as to be insertable
into bore 72 of coupling portion 42 of targeting device 40.
[0071] Reference is now made to FIGS. 3A and 3B, which are
schematic illustrations of additional configurations of coupling
assembly 62, in accordance with embodiments of the present
invention. In these embodiments, blocking element 70 comprises a
blocking element 170. As shown in both FIGS. 3A and 3B, blocking
element 170 is shaped as a small protrusion on an inner aspect of
coupling assembly 62. For some applications, as shown in FIG. 3B,
coupling element 66 is configured such that a portion thereof that
includes engagement surface 76 is proximal to blocking element
170.
[0072] Reference is now made to FIG. 4, which is a schematic
illustration of a detent comprising a snap-like coupling element
200, in accordance with an embodiment of the present invention. In
this embodiment, coupling element 66 comprises snap-like coupling
element 200. Coupling surface 74 of coupling element 200 comprises
one or more movable engagement elements 210, such as spring-loaded
ball bearings. An inner surface of proximal end 50 of bone fixation
device 48 is shaped so as to define one or more indentations 212,
corresponding to engagement elements 210. Indentations 212 are
adapted to receive engagement elements 210, in order to couple
coupling element 200 to proximal end 50. Activator tool 80 is used
to apply pressure to and rotate snap-like coupling element 200 in
order to engage engagement elements 210 with indentations 212, and
to disengage the engagement elements from the indentations.
[0073] Reference is again made to FIG. 2. Coupling element 66
typically comprises a substance having a high strength, such as a
metal, in order to strongly couple coupling portion 42 of targeting
device 40 to proximal end 50 of bone fixation device 48. The
substance is typically radiopaque. A length L1 from a distal end 84
to a proximal end 86 of coupling element 66 is typically less than
about 15 mm, such as less than about 11 mm or less than about 9 mm.
Typically, a distance D1 from proximal end 86 of coupling element
66 to a proximal end 88 of bore 72 is greater than about 25 mm,
such as greater than about 30 mm, greater than about 35 mm, or
greater than about 45 mm, e.g., about 75.3 mm.
[0074] Coupling assembly 62 typically further comprises a generally
radially symmetrical support element 90, which is shaped so as to
define a connection support region 92 and a generally
cylindrically-shaped attachment region 94. Support region 92
engages coupling element 66 when the coupling element is tightened.
Attachment region 94 attaches support element 90 to coupling
portion 42 of targeting device 40. Coupling assembly 62 typically
comprises a substance having a high strength, such as a metal.
[0075] In an embodiment of the present invention, chamber 64 is
shaped so as to define one or more holes 96 extending between (a)
inside the chamber, and (b) outside of coupling portion 42 of
targeting device 40. For some applications, attachment region 94 is
also shaped so as to define holes 96. Holes 96 are typically useful
for facilitating cleaning of chamber 64 between uses, such as by
flushing chamber 64 with a cleaning solution via holes 96.
[0076] In an embodiment, a longitudinal axis of coupling portion 42
of targeting device 40 diverges by an angle alpha from a
longitudinal axis of bone fixation device 48. For some
applications, alpha is between about 2 and about 6 degrees (e.g., 4
degrees), or greater than 6 degrees, e.g., 10 degrees.
[0077] Reference is now made to FIG. 5, which is a schematic
illustration of a targeting device 100, in accordance with an
embodiment of the present invention. Targeting device 100 is
generally similar to targeting devices known in the art, such as
targeting device 10, described hereinabove with reference to FIG.
1. However, unlike in the prior art devices, a coupling element
102, such as a screw, for attaching targeting device 100 to a bone
fixation device 104, such as an IM nail, has a length L2 from a
distal end 106 to a proximal end 108 of screw 102 that is less than
about 30 mm, such as less than about 15 mm, less than about 11 mm,
or less than about 9 mm. A screwdriver 110 having an elongated
shaft 112 is provided for tightening and loosening screw 102. For
some applications, screw 102 and a distal tip 114 of screwdriver
110 are magnetized, to aid in insertion and removal of screw 102
through an elongated bore 116 of targeting device 100.
Alternatively or additionally, distal tip 114 comprises gripping
elements to aid in insertion of screw 102. Typically, a distance D2
from proximal end 108 of screw 102 to a proximal end 118 of bore
116 is greater than about 25 mm, such as greater than about 30 mm,
greater than about 35 mm, or greater than about 45 mm, when screw
102 couples targeting device 100 to bone fixation device 104.
[0078] As appropriate, techniques described herein are practiced in
conjunction with methods and apparatus described in U.S. patent
application Ser. No. 10/616,218, filed Jul. 8, 2003, entitled,
"Intramedullary nail system and method for fixation of a fractured
bone," which is incorporated herein by reference.
[0079] As appropriate, dimensions of various components described
hereinabove are varied in accordance with the dimensions of a bone
which is being treated. For example, smaller bones (e.g.,
phalanges) may be treated with smaller components.
[0080] It will be appreciated that although some embodiments of the
present invention have been shown and described herein for use in a
femur, these embodiments may be adapted for use in other bones of
the extremities, such as the tibia and humerus, mutatis mutandis.
It will also be appreciated by persons skilled in the art that the
present invention is not limited to what has been particularly
shown and described hereinabove. Rather, the scope of the present
invention includes both combinations and subcombinations of the
various features described hereinabove, as well as variations and
modifications thereof that are not in the prior art, which would
occur to persons skilled in the art upon reading the foregoing
description.
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